Explanation:
NGC 3199 lies about 12,000 light-years away,
a glowing cosmic cloud in the southern constellation
of Carina.
The nebula is about 75 light-years across in this haunting,
false-color view.
Though the deep image reveals a more or less complete
ring shape, it does look very lopsided with a much brighter edge
at the lower right.
Near the center of the ring is a
Wolf-Rayet star, a massive, hot,
short-lived star that generates an intense stellar wind.
In fact, Wolf-Rayet stars are known to create nebulae
with interestingshapes as their powerful winds sweep
up surrounding
interstellar
material.
In this case, the bright edge was thought to indicate a
bow shock
produced as the star plowed through a uniform medium, like a boat
through water.
But measurements
have shown the star is not really moving directly
toward the bright edge.
So a more likely explanation is that the
material surrounding the star is not uniform, but
clumped and denser near the bright edge of windblown NGC 3199.